The field of the disclosure relates generally to motorized apparatus and, more particularly, to motorized apparatus for inspecting and/or repairing rotary machines.
At least some known rotary machines, such as turbines for aircraft engines and gas and steam powered turbines for industrial applications, include an outer case and at least one rotor that carries multiple stages of rotating airfoils, i.e., blades, which rotate with respect to the outer case. In addition, the outer case carries multiple stages of stationary airfoils, i.e., guide vanes. The blades and guide vanes are arranged in alternating stages. In at least some known rotary machines, shrouds are disposed on the radially inner surfaces of a stator to form a ring seal around tips of the blades. Together, the blades, guide vanes, and shrouds define a primary flowpath inside the compressor and turbine sections of the rotary machine. This flowpath, combined with a flowpath through the combustor, defines a primary cavity within the rotary machine.
During operation, the components of the rotary machine experience degradation. Accordingly, for at least some known rotary machines, periodic inspections, such as borescope inspections, are performed to assess the condition of the rotary machine in-between service intervals. Examples of damage observed during inspections include wear (e.g., from incursion of blade tips into the shrouds, particle-induced erosion, water droplet induced erosion, wear due to sliding contact between stationary components), impact (e.g., spallation of thermal barrier coating (TBC) or environmental barrier coating (EBC) from turbine-section components, leading edge burring/bending of compressor blades), cracking (e.g., thermal fatigue, low-cycle fatigue, high-cycle fatigue, creep rupture), edge-of-contact damage between stationary parts, oxidation or hot corrosion of high-temperature metallic sections, static seal degradation, and creep deformation (e.g., of guide vane sidewalls/airfoils, blade platforms, and blade tip shrouds).
During service intervals, the rotary machines are at least partially disassembled to allow repair and/or replacement of damaged components. For example, damaged components of at least some known rotary machines are primarily repaired at overhaul or component repair facilities, with only limited intervention conducted in the field. Processes used to repair compressor and turbine flowpath components include surface cleaning to remove accumulated dirt and oxidation products, stripping and restoration of coated surfaces, crack repair, section replacement, and aero contouring and smoothing. Repairing the components during service intervals reduces the cost to maintain the rotary machine because the cost to repair components is sometimes less than the cost to replace the components. However, sometimes, the components run past their repair limits between planned service intervals. In addition, sometimes, heavily distressed components fail and cause an unplanned outage.
For at least some known rotary machines, a tethered device, such as a borescope, is inserted through an opening of the rotary machine and manipulated within a cavity of the rotary machine for inspection. However, at least some known tethered devices do not access all locations of the rotary machine. In particular, some non-rotating components in at least some known rotary machines are difficult to access with a tethered device. Furthermore, damage detected during inspection is typically unmitigated until the machine is at least partially disassembled for scheduled service.